Left ATT to join the TMO and now I think I'm regretting it. 3-4 times now my 4S has displayed either no service or searching. Each time I've rebooted my phone and service came back. The longest I was at "No Service" was maybe 30-45 minutes. I had to eject my SIM - do a reinstall and then everything was OK. At times, If I am in my office basement, I lose service. Everything that didn't or wasn't happening with ATT. I did a check for map coverage before I changed and it seemed to be OK. Also asked did searches and a good %age of those that switched seemed to be happy. I've read that maybe it could be the SIM. Is there a way to pinpoint the problem? I really didn't want to but if I upgrade to the new iPhone coming out, will that maybe help me out with spotty service? Thanks!